In the past, sulfurized sperm oil was widely used as an additive in many lubricant formulations such as in gear oil, worm, and spur gears, automatic transmission fluids, metal-working lubricants and the like. Sulfurized sperm oil is especially useful for improving extreme pressure properties while providing excellent lubricity and some degree of rust-inhibition in motor oils, gear lubricants, and rolling oils. However, the sulfurized sperm oils have been replaced in recent years by other sulfurized compositions as a result of the reduction in availability of sperm oil and increased cost. Sulfurized olefins do not always exhibit the degree of lubricity which is necessary in many applications.
Habiby, in U.S. Pat. Nos. 3,926,822 and 3,953,347, describes a composition comprising a sulfurized mixture of a fatty acid ester of a mono- or polyhydric alcohol, a fatty acid and an aliphatic olefin. Newingham et al, in U.S. Pat. Nos. 3,825,495 and 4,180,466, teaches lubrication of controlled-slip differentials with a composition comprising a cosulfurized blend of a triglyceride and a monoolefin. Recchuite, in a series of U.S. Patents, for example, U.S. Pat. Nos. 4,166,796, 4,166,797, 4,321,153 and 4,456,540 teaches compositions comprising a cosulfurized mixture of triglycerides and an olefinic hydrocarbon. The '540 patent also recites the presence of a fatty acid in the reaction mixture. In U.S. Pat. No. 4,166,795, Recchuite teaches the reaction product of sulfur, lard oil, polyisobutylene oligomers and optionally another unsaturated material. All of these patents describe the use of these sulfurized mixtures in lubricants. Other sulfurized fatty acid esters are described in Lincoln et al, U.S. Pat. No. 2,113,811; Wasson et al, U.S. Pat. No. 2,672,444; Eby, U.S. Pat. No. 2,680,718; Wakim, U.S. Pat. No. 3,986,966; Zipf, U.S. Pat. No. 4,036,769; Hotten, U.S. Pat. No. 4,053,427; and Jackisch, U.S. Pat. No. 4,176,072 and in PCT Publication W086/06371.
Numerous patents describe the use of various partial esters of polyhydric alcohols as friction modifiers, emulsifiers, lubricity agents and corrosion inhibitors. These include Adams et al (U.S. Pat. No. 2,268,234), Schwartz (U.S. Pat. No. 2,412,633), Barnum (U.S. Pat. No. 2,564,423), Adelson et al (U.S. Pat. No. 2,628,941), Wasson et al (U.S. Pat. No. 2,672,444), Bondi et al (U.S. Pat. No. 2,788,326), Wisotsky (U.S. Pat. No. 4,505,829) and U.K. patent application 2,038,355.